Upgrading an old Joomla site that is down

[millerlu]

I inherited an old Joomla site that just went down and I am trying bring it back up. Currently the site gives a 503 error. The site is running Joomla 2.5.26, which I know is very old! I have talked to the hosting company and they have recently upgraded the server to use PHP 7.4.33. I believe the site was using PHP 5.6 before the upgrade. The hosting company can not go back to 5.6. I believe that is why it is down and giving a 503 error. I can not load the administrator page either. I believe I need to upgrade to a newer version of Joolma that supports PHP 7 like Joolma 3.X and then upgrade more from there.

If I remove the .htaccess file the site redirects to /installation/index.php and gives these errors:

Fatal error: Uncaught Error: Call to undefined method JHtml::getJSObject() in public_html/libraries/joomla/html/behavior.php:235
Stack trace: #0 public_html/libraries/joomla/html/html.php(222): JHtmlBehavior::tooltip()
#1 public_html/libraries/joomla/html/html.php(135): JHtml::call(Array, Array)
#2 public_html/installation/template/index.php(26): JHtml::_('jhtml.behavior....')
#3 public_html/libraries/joomla/document/html/html.php(531): require('/home/customer/...')
#4 public_html/libraries/joomla/document/html/html.php(588): JDocumentHTML->_loadTemplate('/home/customer/...', 'index.php')
#5 public_html/libraries/joomla/document/html/html.php(414): JDocumentHTML->_fetchTemplate(Array)
#6 public_html/libraries/joomla/document/html/h in public_html/libraries/joomla/html/behavior.php on line 235

I tried upgrading to 2.5.28 and 3.5.1 and both upgrade and full packages via FTP with no change. After each upgrade attempt I restored back to a previous backup to keep the site as clean as possible.

I also installed a local Linux server and installed PHP 5.6 and MySQL on it and restored the server content and database to it, thinking if I could get that up I could use the administrator page to do the upgrade and there and then move it back to the hosted site. I also tried this with XAMMP 5.6.40. Both got the same result when I removed the .htaccess file. The site redirects to /installation/index.php and gives these errors:

Deprecated: iconv_set_encoding(): Use of iconv.internal_encoding is deprecated in public_html/libraries/joomla/string/string.php on line 28
Deprecated: iconv_set_encoding(): Use of iconv.input_encoding is deprecated in public_html/libraries/joomla/string/string.php on line 29
Deprecated: iconv_set_encoding(): Use of iconv.output_encoding is deprecated in public_html/libraries/joomla/string/string.php on line 30
Fatal error: Call to undefined method JHtml::getJSObject() in public_html/libraries/joomla/html/behavior.php on line 235

I am kind of at a loss for what to try next, any ideas?
Thanks,
Luke

[gws]

Rename the installation folder to something like instalationold and see what happens. If you haven't got to far with your efforts Wampserver is way better than Xamp. https://wampserver.aviatechno.net/?lang=en

[millerlu]

Rename the installation folder to something like instalationold and see what happens. If you haven't got to far with your efforts Wampserver is way better than Xamp. https://wampserver.aviatechno.net/?lang=en

Do you mean rename installation before I try an FTP update or after?
It looks like Wampserver is only for Windows, I am on a Mac.

Thanks,
Luke

[AMurray]

MAMP is the equivalent for MacOS. (Google it, you should find it easily).